Metronome



May 8, 1945.

G. c. ENGEL ETAL 2,375,294

METRONOME Filed April 11, 1942 3 Sheets-Sheet 1- May 8, 1945.

G. C. ENGEL ETAL METRONOMEl Filed April l1, 1942 3 Sheets-Sheet 2 May 8, 1945. G. c. ENGEL ET AL 2,375g294 METRoNoME Filed April 11, 1942 3 sheets-sheet 5 i5 Z K Patented May 8, 1945 METaoNoME George C. Engel, Ridgewood, N. J., and Frank L. Eidmann, deceased, late of Princeton, N. J., by'Et-hel I-. Eidmann, executrix, Princeton, N. J., assig-nors to General Time Instruments Corporation, New York,- N. Y., a corporation of Dela- Waile.

iiclaims.

This invention relates to metronomes and in particular to an improved device for producingv audible signals at regular intervals in order to facilitate the execution of musical compositions.

The audible signals produced by a metronome are commonly of two types: a series of beats which indicate the tempo of the music, for example 50 beats per minute; and a series of accents which indicate the rhythm ofthe music or the beginning of each measure. The accents are commoniy sounded simultaneously with every second, third, fourth or sixth beaty depending on whether the compositioncallsfor`2l/4, 3/4, 4/4 or 6/8 time, respectively. -1 v It is a 4prin'fiary 'object of this invention to provide an improved electrically driven metronome which can be adjusted to producea predetermined' number of beats per minute, together with the desired accents.

A further object is to provide an improved variablev speed transmission which is adaptedv for use in a metronome.

Another object is toprovide improved accent sounding mechanism for a metronome which can be shifted from one kindof time or accent to another without stopping the metronome.

Still another object is to provide for a -metronome an improved non-,dampening bell striking mechanism.

It is also an object to provide a metronome of inexpensive and of simple construction which may be driven by the small amount of power produced by the usual electric clock motor.

Other objects, features and advantages will become apparent as the description proceeds. y

In the drawings in which like reference numerals refer to like parts,

Fig. l is a `front elevation of a preferred embodiment of this invention, the housing being removed;

Fig. 2 is a plan view of the device shown in Fig. 1;

Fig. 3 is a side elevation, partly in section, of thedevice shown in. Figs. 1 and 2;

Fig. 4 is a section taken along line 4-4 of Fig. 3;

Fig. 5 is an enlarged section of a detail taken along line- 5--5 of Fig. 3;

Fig. 6 is a section taken along line l-6` of Fg.3; f'-

Fig. 'lr is a section taken along line 1--1 of Fg 3.; l

Fig. `8 is an .enlarged section taken along line 88 of Fig. 4 showing certain details thereof;

Application Apl'illl, 1942, Serial No. 438,622

. structure.

Fig. 9 is an enlarged plan view taken along line 9-9 ofY Fig. 8;'

Figs. 10, 11 and 12 are sections taken along lines lil-40, II-ll and lZ-IZ- of Fig. 8', showing the different shapes of cams provided; and,

Fig. 13y is a detailed view of the framework for supporting the splined shaft, the friction wheel and other parts being omitted for the purpose of clarity.

Referring now to Figs. l to 4 which show the general relationship` of the parts, the mechanism is mounted on a base I5, and driven by a self'- sta'rting synchronous electric motor I6 which is screwed to the underside of the base. A slotted plate Il is suitably secured tothe front edge of the '-base in perpendicular"relationship thereto, and as shown in Fig. 1, it is provided with a slot 'through which a manually operatedy knob 43 extends. A'plate. 93 is also provided at. the front edge of the base and extends downwardly therefrom, and a rotatable knob is journalled in this plate 93.

Secured to the base l5 are side members I8 and i9 which extend Aupwardly and inwardly andwhich are associated with each other at their upperends by an L-shaped strip 20 which strip is also secured to the upper portion of the slotted plate I'I. The above mentioned parts may be screwed to each other in order to form a rigid A driving pinion 2| is secured to the drive shaft of the motor which extends through the base i5, the pinion being disposed on the upper surface of the base. A gear 22 is mounted on a shaft 23 which is journalled in the base l5 and in the L-shaped strip 2D, the gear 22 meshing with the pinion 2l so that the shaft 23 will be rotated thereby. A conically shaped hard rubber driving member 24 is mounted on the shaft 23. The .base l5 is bent so that the shaft'23 is dis posed at an angle to the slotted plate I1 and so that a line drawn vertically along the surface' of the cone 24, `at that point on the surface which is nearest the slotted plate, will be parallel thereto. The cone forms one element of a variable speed transmission, the other element of which is a friction wheel 25 which is mounted on a splined shaft 2S in axially shiftable rela"- tionship, butwhich friction wheel is constrained to rotate with the shaft byvirtue of the spline 2l which cooperates with a corresponding key on the friction wheel. The splined shaft' 26 is ro"- tatably mounted in a frame' designated. generally by the reference numeral 28, the framework being pivotally mounted so that the shaft-may be moved bodily toward and away from the surface'of the cone 24. As shown in Fig. 13, the framework comprises a vertical member 29 to the lower end of which is secured a horizontal member 38. The upper end of the vertical member 29 is received in and pinned to a socket 3| which forms a part of an upper horizontally disposed member 32. The reduced ends of the Shaft 26 are received in and journalled in the horizontal members 38 and 32. The framework 28 is pivotally mounted in the base I and in a bracket 33 which bracket is formed by a forwardly and upwardly extending portion of the L -shaped strip 20,'the reduced ends of the vertical member 29 extending through the horizontal members 39 and 32 and being received in apertures provided inthe base I5 and in the bracket 33 for that purpose. A pin 34 extends upwardly from the bracket 33 and is engaged by a leaf spring 35 which is anchored by a screw 36 to the upper surface of the bracket 33 so that the framework 28 as a whole and the friction wheel 25 will be biased against the surface of the cone 24,

The friction wheel as shown in Fig. 8 comprisesl a hub member 31 which is provided with two flanges 38, a rubber tire or ring 39 being held between the flanges and extending outwardly beyond the same for engagement with the surface of the cone 24. An annular groove 4D is provided in the upper portion of the hub member 31 and is adapted to receive the spherically shaped end 4| of the manually operable sliding member which is2 generally designated by the reference numeral As shown in Fig. 5 the sliding member 42 consists essentially of a bar which has been turned so that its forward end forms the above mentioned knob 43, and so that it is also provided with an intermediate portion 44 of reduced diameter. The intermediate portion 44 is provided with screw-threads 46 upon which a nut 41 is disposed. A diamond shaped plate which serves A and 52, are confined between the knob 43 and the nut 41. The collar 58 slides in the slot 53, and the front and rear surfaces of the plate I1 are engaged by the pointer 48 and the spring plate 49, the whole assembly being secured together for a minimum amount of play so that for any given position of the sliding member 42, the friction wheel 25 will engage the cone 24 at a predeteru mined point. The plate I 1 is provided on its rear surface with a series of depressions 54 which are engaged by projections 55 which are stamped in the spring plate 49 in order that the position of the sliding member 42 may be Xed. Indicia 56 are stamped on the front surface of the slotted plate I1 which indicate the number of revolutions per minute of the friction wheel 25 when held in the vertical position indicated.

The beats are produced by a hammer 6|! which strikes a sounding board 6| which is suitably secured to the side member I8. The sounding board may be of any suitable material such as a reenforced sheet of phenol formaldehyde con densation product. The hammer 68 is actuated once for each revolution of the splined shaft 28 so that the indicia 56 will indicate not only the speed of the shaft but also the tempo or number of beats per minute.

The hammer 60 is mounted on an arm 65, the arm being secured to a hub member 62 which is rotatably journalled on the lower horizontal member 38. The forward end of the arm 65 is engaged by a cam 63 which is secured to the lower portion of the spline shaft 26. A spring 66 extends between the arm 65 and a pin 61 which is mounted on the base I5. It will be seen that the spring biases the forward end of the arm 65 against the cam 63, and the hammer 6I) against the sounding board 5I. As the cam rotates, the hammer is withdrawn from the sounding board against the bias of the spring 66, until the drop face of the cam is rotated past the end of the arm 65, at which time the spring causes the hammer to strike the board to sound a beat. The spring E6 also cooperates with the leaf spring 35 to urge the friction wheel 25 against the cone 24.

The accent is indicated by a hammer 19 which strikes a bell 1I, the bell being suitably secured to the side member I9 as shown in Fig. 4. The hammer 19 is mounted upon an arm 12, the arm being secured to an arbor 13 which is journalled in the base I5 and in a plate 14, the latter plate being mounted above the base and spaced therefrom by means of spacers 15. The hammer is driven from the splined shaft 26 by means which include a single toothed wheel 16 which is secured to the shaft 26 at a point beneath the cam 63. A star wheel 11, mounted on a shaft 18 journalled in the base I5 and the plate 14, is engaged by the single toothed wheel 16, and rotated to the extent of one tooth for each complete revolution of the splined shaft 26.

A sleeve 19 is mounted on the shaft 18 in axially shiftable relationship thereto, and is provided with a plurality of cams 80, 8|, 82 and 83, each of which cams is provided with a plurality of drops.

As shown in Figs. 9 to 12 inclusive, the cam 86 has two drop surfaces, and the cams 8|, 82 and 83 have 3, 4 and 6 drop surfaces respectively. The sleeve 19 is keyed to the shaft 18 by means of a key 84 so that the cams will be rotated with the star wheel 11. A coil spring 85 surrounds the shaft 18 and serves to urge the sleeve 19 and its associated cams downwardly against the star wheel as shown in Fig. 8.

A rider B6 is provided for selectively engaging one or the other of the cams 80--83, the rider being secured to a rock shaft 81 which is journalled in the base I5 and the plate 14. An upper collar 88 and a lower collar 89 are secured to the rock shaft 81, and as shown in Fig. 8 a coil spring 981s disposed on the rock shaft 81 and is conned between the lower collar 89 and the plate 14 so as to urge the rock shaft downwardly to the limit of its motion as determined by the engagement of the upper collar 86 by the plate 14. The rock shaft 81 is slidably mounted in the base I5 and in the plate 14. In this neutral position of the parts. as shown in solid lines in Fig. 8, the rider 86 clears the cams so that the hammer 1U is not operated. The vertical position of the rock shaft 81 is determined by a cam 9| which engages the lower end thereof.

A U-shaped bar 96 is secured to the collars 88 and 89, the intermediate portion of which bar is disposed parallel to the rock shaft 81, and extends through an aperture |00 in the plate 14. A spring 91 is tensioned between the U-shaped bar 95 and a pin 98, the pin being mounted in the plate 14. The spring 91 biases the cam rider against one orthe other of the cams BEI- 83, and also maintains the U-shaped bar in engagement with the arm 12 of the hammer 10. The bar 96 and the rider 86 may be constructed from a single piece of bar stock as shown in Figs. 8 and 9.

A coil spring 99 is provided for the arbor 13 to bias .the hammer 11). away trom the'hell. and

to maintain `the :other .end mi the arm 12 .in :eneasement' with tlf-.shaped Joa-m96. The tension of this :coil spring :59 lis less than :the tension-of the spring 91. When the :rock :shaft z8?! `is .maintained in eleva-ted .position so that thel rider 86 engages one of sthecams, it will .be .seen ythat each :time the rider drops loff fof ya .drop face, Athat the bar 9'6 :will engage vand rotate the arm l2. The inertia of the-hammer 70..'and or the yarm will cause the .arm .to :be rotated in :the rcounterclockwisedirection beyond the solidline position shown in Fig. 9 'so `that the-hammer will strike the bell as shown by the fbroken lines. The rebound .of the hammer from the ybell vwill :be aided by the coil spring 8.9 which will also ser-ve to maintain the hammer away from the bell Aso tthat the .tone of `rt-hebell wil-lrnot be dampened.

The cam B-I is :secu-red rto a shaft -92 which shaft is journalled in the ,plate 93 and inI a U- shaped bracket .84, the bracket being secured to the underside Yof the base 115. T-he knob '85 is secured to the shaft V92 .forwardly of the plate 93, and a spring arm yIIJI is secured to the rear .end of the `'shaft :9.2. As shown in .Fi-gs. 57 and 8 the `rear half of the U-shaped bracket 94 is pro vided with a seriesoffapertures |03, and the spring arm IUI is provided with a projection |132 which is adapted to engage one or the other of the apertures |33 to maintain the cam .SI 'ein a predetermined position. As shown in Fig. 1 the plate v83 is provided on its fron-t .surface with the numerals 2, .3, 4 and 6. each one lof which numerals corresponds with yone .oi the apertures I 03. When the knob is rotated so that the arrow on the knob points to one of the numerals. the

cam will cause the rock shaft 81 to be elevated so that the rider 8'6 engages the correspondiner cam. When the arrow points to 2. cam 83 will be engaged.' Cam 83 has sin teeth which will re I The circuit to the motor It 4isopened and vclosed by rotating the knob 9.5. A stationary contact IM is secured yto an insulatim;r strip MI5 mounted on the upper surface 'of the base I'E as shown in Figs. 6 and r'-7.

H2B is also secured to the insulating strip imi., and is biased downwardly to .make contact with the stationary contact |04. An insulating rod Il is vertically and slidably disposed in the base I5 and in theconnecting portion of the U-shaped bracket .94, .and is provided with an enlarged por tion at its upper end which prevents it from dropping through 4the base I5 through which. it extends. The upper portion of the insulating. rod .|01 engages the resilient .con-tact member .H16 and the lower end of the rod is engaged by a radially disposed face |08 provided -on the Icam 9i. It will be seen that as the knob `535 is rotated to the limit of its rotation, as 'determined by theA stop IUS the insulating rod Il will .be pushed A resilient contact member vmer `t0 have been described above.

is .rotated in :the clockwise direction 'to on position, thereby `.permitltingg the contact 3h06 .to drop :and A,to 'close the motor circuit. The beat hammer .60 Awill ethen be operated by the cam i63 to .produce ta :given number :of beats per minute, as indicated 'by the cooperation of the Pointer 48 with the indicia ifi. The tempo may be varied by lshifting :the position rof the sliding knob '43.

In this position of the parts (i. e., whenthe arrow on the 'knob V95 points to "-on) the ;a.ccent is not sounded because the vrider -86 is maintained fclear K.of 'the cams -80 to 83, as show-n in Fig-. 8. If it is desired to operate the accent sounding mechanism for 4/4 time, the knob 95 ist-rotated to its 4 vfpfasition. causes the rock :shaft 81 `andthe rider ltil to be yelevated to a `position wherein the rider will be lopposite the cam 118.1.. In the event that the ,position of .the lowermost -carn 83 tends to block the shifting of the .ride-r, the whole group of cams will be elevated with the rider against .the bias of spring 85. This position of rthe par-ts is show-n in broken lines in Fig. 8. Subsequent rotation of .the cams will permit the spring 85 to force the group downwardly, step by step, :to the 'normal solid line position, after which the accent will be sounded on every Ifour-th beat as desi-red..

The rid-er 86 may be `shifted downwardly 'by rotating the zknob .95 and the .cam 9i. In case an adjacent cam blocks the downward movement. the laction will be delayed, but the spring 9D will ycause a step by step downward movement during the subsequent .revolution of the group .of cams. The axially shiftable mounting of the cams and of the rider permits the manual setting of the knob 9.5 at any time.

As shown vin Fig. 9, the parts are adjusted .for an accent on every sixth beat. the cam Bil having two drop surfaces.

The non-dampening operation of the yaccent hammer .'10 and the operation of the beat ham- The parts are preferably timed so that the accent is produced simultaneously with .a beat, this timing beingv effected at the factory by adjusting `the angular position of the cam 63 with respect to the single toothed wheel l-B..

It will be obvious to those skilled in the art that various modifications and changes' in the size, shape and proportion `of the parts may be effected without departing from the spirit of this invention. The above description relates tok a preferred embodiment only and is not intended to limit the scope of this invention which is deiined in the appended claims.

What is claimed as new is:

1. A metronome comprising constant speed driving means, a conical friction element driven thereby, a pivotally mounted frame adjacent said conical friction element, a shaft journalled in said frame. a friction wheel mounted on said upwardly, thereby opening the circuit between To operate the metronome, the knob A Conductors IIU and. III extend shaft for cooperation with saidyconical friction element, a cam associated with said shaft and a striker arm actuated by said cam, said striker arm being pivotally mounted on said frame, and a spring tensioned between said striker arm and a xed point so as to `urge the end of said striker arm against said cam and the periphery of said cooperating friction wheel against the surface of said-conical friction element.

.2. A metronome comprising a pivotally mounted beat hammer and a pivotally mounted accent hammer, cam means for actuating said beat hammer and cam means for driving said accent hammer, and variable speed driving means .for each of said cam means, said last mentioned cam means comprising a series of co-axially secured cams, a cam rider for cooperation with one of said cams, means to shift the position of said cam` rider so that it will selectively engage' one or the other of said cams, said cams being axially shiftable so as to permit displacement thereof by said rider when an adjacent cam blocks the free axial movement of said rider from one cam face to the next, and a spring for shifting said cams back to their original position when said adjacent cam has been rotated to an extent so as to permit relative movement of said rider and of said cams'.

3. A metronome comprising a pivotally l mounted beat hammer and a pivotally mounted accent hammer, cam means for actuating said beat hammer and cam means for driving said accent hammer, said last mentioned cam means comprising a group of co-axially arranged cams, an axially displaceable rock shaft, a cam rider for selective cooperation with one or the other of the cams of said group, said cam rider being secured to said axially displaceable rock shaft, control means engaging said rock shaft to shift its axial position upwardly, and a spring engaging said rock shaft for urging the same downwardly against said control means, whereby the downward movement of said cam rider from one cam to another subsequent to the operation of said control means may be delayed until such time as said rider is not blocked by the projecting portion of an adjacent cam.

fl. In a metronome having an accent hammer, means for actuating said accent hammer at variable intervals, said means including a cam shaft, a plurality of cams keyed to said shaft in axially shiftable relationship, stop means secured to said shaft for limiting the movement of said cams in the downward direction, a displaceable rider for selectively engaging one or the other of said cams, second stop means for limiting the movement of said rider in the downward direction, means for adjusting the position of said second mentioned stop means, the positions of said rider and of said cams with respect to each other during and after the operation of said adjusting means remaining the same when the relative motion of one with respect to the other is blocked by the projecting portion of an adjacent cam, and separate means to urge said rider and said cams against their respective stop members so that the positions of said rider and of said cams may be shifted with respect toeach other when said adjacent cam has been rotated so as to clear said rider, and means for rotating said cam shaft.

5. In a metronome having a bell and a pivotally mounted hammer for said bell, a cam rider adapted to contact said hammer, means to bias said hammer into contact with said cam rider, a group of cams cooperating with said cam rider, a spring for urging said cam rider into contact with one or the other of the cams of said group, said spring being stronger than said hammer biasing means so that as said rider drops off of one of said cams, a quick operative stroke will be imparted to said hammer, said cams each being provided with a dierent number of drop surfaces, and means to adjust the axial position of said rider with respect to said cams so as to determine the frequency with which said hammer strikes said bell, depending upon the munber of drop surfaces ofthe particular cam engaged by said rider in its adjusted position, l

6. A metronome comprising a synchronous electric motor, a variable speed transmission device associated therewith, a beat hammer and an accent hammer driven by said variable speed transmission device, means to adjust the operation of said accent hammer, a switch for said motor, and common control means for said motor switch and for said adjusting means.

7. A metronome comprising a synchronous electric motor, variable speed transmission means associated therewith, a beat hammer and an accent hammer driven by said variable speed transmission means, manually rotatable means vfor regulating the frequency of operation of said accent hammer, a switch for said motor. and an actuating member associated with said switch and extending into the path of said manually rotatable means, the parts being so constructed that when said manually rotatable member is rotated in one direction from a neutral position, said motor switch is opened, and when rotated in the opposite direction from said neutral position, the frequency of operation of said accent hammer is regulated.

8. In a metronome having an accent hammer. a group of cams, a cam rider selectively cooperating with one or the other of the cams of said group to control the operation of said accent hammer, a control cam for adjusting the position of said cam rider with respect to said group of cams, said control cam being provided with a radially extending face. an electric clock motor for driving said group of cams, and switch means for said motor including a switch actuating member extending into the path of said radially extending face.

9. In a metronome having an accent hammer. a group of cams, a cam rider selectively cooperating with one or the other of the cams of said group to control the operation of said accent hammer, a control cam for adjusting the position of said cam rider with respect to said group of cams, said control cam being provided with radially extending face, -an electric clock motor for driving said group of cams, a switch for said motor, a switch actuating member extending into the path of said radially extending face whereby rotation of said control cam will cause said motor switch to be opened, and means to maintain said control cam in one or the other of a nlurality of predetermined positions corresponding to those positions in which said rider engages one or the other of said cams, and in that position in which said radially extending face maintains said motor switch in open circuit position.

l0. A metronome comprising time responsive driving means, a cone driven thereby at a constant rate of speed, a splined shaft spaced from said cone and substantially parallel to an adjacent portion of the surface thereof, a friction wheel mounted on said splined shaft in axially shiftable relationship and engagingr the surface of said cone, and means to shift the position of said friction wheel along said splined shaft to regulate the speed of rotation of said splined shaft, said means including a slotted plate dirposed parallel to said splined shaft. and a sliding member extending through said slotted plate and engaging said friction. wheel, said sliding member being provided with plates embracing the opposite surfaces of said slotted plate, one of said surfaces being provided with a series of depressions, whereby one of said plates may selectively` engage one or the other of said depressions to maintain said sliding member in a predetermined position.

two plates secured to said sliding member and 10 resiliently embracing the opposite surfaces of said slotted plate, and signal producing means driven by said shaft for operation at regular intervals as determined by the speed of said shaft and the setting of said sliding member.

GEORGE C. ENGEL. ETHEL I. EIDMANN, Eecutri of the Last Will and Testament of' Frank L. Eidmann, Deceased. 

